Computers, televisions, telephones and other electronic product contain large numbers of essential electronic semiconductor devices. To produce electronic products, hundreds or thousands of semiconductor devices are manufactured in a very small space, using lithography techniques on semiconductor substrates, such as on silicon wafers. Due to the extremely small dimensions involved in manufacturing semiconductor devices, contaminants on the semiconductor substrate material, such as particles of dust, dirt, paint, metal, etc. lead to defects in the end products.
Existing automated semiconductor processing system use robots, carriers, rotors, and other devices, to move and process wafers. These systems are designed to avoid creating particles which may contaminate the wafers. However, even with careful design, material selection, and system operation, particles may still be created by the moving parts of the systems, or by the contacting or abrasion of wafers by components of such systems.
Many automated semiconductor processing systems use centrifugal wafer processors, which spin the wafers at high speed, while spraying or otherwise applying process fluids and/or gases onto the wafers. The rotors typically hold a batch of wafers in a parallel array during the spin/spray process. It is important to have the process liquids contact the wafer surfaces in a substantially uniform way, so that all useable surfaces of the wafers receive substantially consistent processing, and so that all wafers within the batch of wafers in the rotor (as well as subsequent batches) are generally uniformly processed. As a result, it is advantageous for the rotor in the process chamber, as well as any tray or carrier installed into the rotor, to have a structure which allows the process liquids and/or gases to be sprayed through and onto the wafers. On the other hand, the wafers must be adequately supported to avoid excessive stress and wafer breakage. Highly reactive or corrosive chemicals are often used in wafer processing. Consequently, rotors and carriers have often been made of Teflon (fluorine containing resins), a corrosion resistant material. However, Teflon lacks the strength and stiffness of other commonly used materials, such as stainless steel. These factors present design engineering challenges in providing rotors or carriers which are strong and rigid enough to carry and spin wafers, while also minimizing interference with the inflow/inspray of process fluids or gases.
Accordingly, there is a need for improved apparatus and methods for handling and processing wafers.